Now I am no fan of ARMS mounts, so I’m pretty biased about that. I have this MK12MOD1 upper where I use the period correct ARMS 12H rings. I generally try not to remove QD scopes unless I have to, especially so with ARMS mounts.
On Saturday I found that after having removed the scope and reattached it previously, my zero had shifted 4 inches left at 100 yards. I figured this was a fluke and seemed excessive even for ARMS, so I removed the scope, cleaned the upper and mounting point on the scope rings, and remounted it. That moved the group 2 inches right and an inch down.
Quick detach mounts are awesome, but make sure if you use one, that it does return to zero. I am going to stick with Larue mounts on any of my serious use ARs.
For rifles like the AR15 I prefer to have my optics on quick detach (QD) mounts. These are useful for a number of reasons including, the ability to quickly remove a damaged optic, quick access to iron sights, and being able to switch optics for different roles. Accessories also benefit from being QD so I can add and remove bulky bipods, lights, forward grips easily. The only real downside to quality QD mounts is the price. For me, the price is easily justifiable when I can take off the Aimpoint from one of my AR15s, and put on an NightForce scope and a bipod, and retaining my previous zero.
For optics mounts, I recommend LaRue Tactical. Their mounts have worked well for me. Recently I have been using ADM mounts on my bipods and while I find I have to adjust the mount to fit each rifle’s rail each time I move it, it works well. I didn’t like the new Surefire throw lever on their newer lights as I would accidentally bump it and it would come loose. I do not recommend ARMS mounts due to their being either too loose or too tight on various brands of uppers.